It is common practice, particularly in the automotive industry, to join together two metal preformed panels into a unitary hollow structural unit. A typical unit of this type is the hollow door used in passenger cars and light trucks. These doors customarily comprise an outer and inner metal sheet or panel.
The manner in which the two panels are joined is the subject of this invention. The process of joining or clinching the two panels together is referred to as hemming.
It is important that the hemming procedure results in a firm, vice like grip of the flange of the outer panel with the edge portion of the inner panel. It is also vital that the shape and dimensions of the door are held within prescribed tolerances.